Tyrosine kinase inhibitor (TKI) is a pharmaceutical drug that inhibits tyrosine kinase, an enzyme which transports phosphates from ATP to a protein's tyrosine residue. Therefore, a Tyrosine Kinase inhibitor prevents the phosphate groups from being transferred. Research indicates that mutations which make Tyrosine Kinases constantly active can be a contributing factor in the development of cancerous cells. So, when an inhibitor is used, the cell communication and reproduction is reduced, and cancerous cell growth will be reduced to the point of stopping tumor growth.
Several TKIs have been found to have effective antitumor activity and have been approved and were commercially available in various dosage forms and strengths; for example imatinib, gefitinib, erlotinib, sorafenib, nilotinib, dasatinib, lapatinib, sunitinib, etc.
TKIs in pharmaceutical compositions can be prepared in a variety of different forms. Such drugs can be prepared so as to have a variety of different chemical forms including chemical derivatives or salts. Such drugs can also be prepared to have different physical forms. For example, the drugs may be amorphous or may have different crystalline polymorphs, perhaps existing in different solvates or hydrate states. By varying the form of a drug, it is possible to vary the physical properties thereof. For example, crystalline polymorphs typically have different solubilities from one another, such that a more thermodynamically stable polymorph is less soluble than a less thermodynamically stable polymorph. Pharmaceutical polymorphs can also differ in properties such as shelf-life, bioavailability, morphology, vapour pressure, density, color, and compressibility.
EP Patent No. 0823900B1 discloses quinazoline derivatives such as Gefitinib of Formula I and pharmaceutically acceptable salts thereof viz. hydrochloride salt, dihydrochloride salt, difumarate salt, di-L-tartaric acid salt, dimethane sulfonic acid salt, disulfonic acid salt, di-4-toluene sulfonic acid salt.

PCT Publication WO 2003/072108, discloses crystalline forms of Gefitinib viz. Form-I anhydrous form, Form-2 MeOH solvate, Form-3 DMSO solvate and Form-5 trihydrate.
EP Patent No. 0564409 discloses Imatinib of Formula II and pharmaceutically acceptable salts thereof and process for the preparation of the same.

Imatinib is marketed in many countries as its methanesulfonate salt (imatinib mesylate) under the brand name GLIVEC® or GLEEVEC®. The marketed imatinib mesylate was disclosed in U.S. Pat. No. 6,894,051 (“the '051 patent”) as its alpha-crystal form and a beta-crystal form. The '051 patent also discloses that the beta-crystal form has the advantage that its flow properties are substantially more favorable than those of the alpha-crystal form.
PCT Publication WO2005/075454 discloses various pharmaceutically acceptable salt forms of imatinib, which are exemplified by a tartrate salt (D,L), a hydrochloride salt, a citrate salt, a malate salt, a D-malate salt, a fumarate salt, a succinate salt, a benzoate salt, a benzenesulfonate salt, a pamoate salt, a formate salt, a malonate salt, a 1,5-naphthalenedisulfonate salt, a salicylate salt, a cyclohexanesulfamate salt, a lactate salt, a (S)-lactate salt, a mandelate salt, an (R)-(−)-mandelate salt, a glutarate salt, an adipate salt, a squarate salt, a vanillate salt, an oxaloacetate salt, an ascorbate salt, an (L)-ascorbate salt and a sulfate salt, and discloses a preparation method thereof and their water solubility. However, there is no disclosure about physical or pharmaceutical properties of the salts of imatinib.
Although it is known that the preparation of salt forms may improve the physical or pharmaceutical properties of a basic pharmaceutical active compound, it is not possible to predict which salt forms may possess advantages for a particular purpose prior to the actual preparation and characterization of the salt form.
The discovery of new salts and polymorphic forms of Tyrosine kinase inhibitors can provide new opportunities to improve the synthesis and the characteristics of the active pharmaceutical ingredient (API). Such discoveries can also enlarge the repertoire of materials that a formulation scientist has available for designing, for example, a pharmaceutical dosage form of a drug with a targeted release profile or other desired characteristic.
Accordingly, there remains a need in the art for novel solid forms of tyrosine kinase inhibitors having greater solubility and bioavailability and having desirable pharmacological, pharmacokinetic, pharmacodynamic effects.